Post-Doctoral Associate Oak Ridge National Lab Oak Ridge, Tennessee
Body of Abstract: Increasing interest in plant holobiont theory and microbial invasion ecology has been highlighted in studies on plant–microbe interactions. Plants manipulate their local environment to influence the likelihood of successful microbial invasions. In addition to nutrient exchange through root exudation, a plant can also secrete macromolecules that interact with its microbiome. We have previously shown that Populus trichocarpa small, secreted proteins (PtSSPs) can enter the nuclei of its symbiotic fungal partner Laccaria bicolor. However, the role of PtSSPs during the mutualistic symbiosis and the mechanistic reasoning behind the roles remain unknown. Our functional genomics research revealed that overexpression of PtSSP1 enhanced the colonization of hybrid poplar clone 717-1B4 (P. tremula x P. alba clone INRA 717-1B4) by L. bicolor, whereas overexpression of another PtSSP (PtSSP5) inhibited the colonization of poplar by L. bicolor. Through yeast two hybrid and bimolecular fluorescence complementation assays, we discovered that the PtSSP1 interacted with a Gal4-like transcription factor (TF) in L. bicolor. Currently, we are further characterizing the association between PtSSP1 and the TF. Also, we are testing if the enhanced colonization can promote the root development in hybrid poplar clone 717-1B4. Overall, we demonstrated that PtSSP1 and PtSSP5 played different roles in poplar-Laccaria interactions. Our results provide new knowledge for informing genetic engineering of plants to control associated microbes.